Estimation of electron density, effective atomic number and stopping power ratio using dual-layer computed tomography for radiotherapy treatment planning
Estimation of electron density, effective atomic number and stopping power ratio using dual-layer computed tomography for radiotherapy treatment planning
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DOI：
10.1016/j.ejmp.2018.11.008
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发表时间：
2018-12-01
影响因子：
3.4
通讯作者：
Teshima, Teruki
中科院分区：
文献类型：
--
作者：
Ohira, Shingo;Washio, Hayate;Teshima, Teruki
目的：评估使用双层计算机断层扫描（DLCT）系统定量测量相对于水的电子密度（P-e/P-e，P-w）、有效原子序数（Z（eff））和相对于水的阻止功率比（SPBw）的准确性。管电压、旋转时间、CTDIvol和扫描模式）和不同的参考材料。然后，重建电子密度P-e/p（e，w）和原子序数Z（e）（ff）图像，并确定每种参比物质的值。基于这两个值，计算SPA（w）。结果：p（e）/ p（e，w）（r = 1.000）、Z（e）（ff）（r = 0.989）和SPA（w）（r = 1.000）与理论值之间均呈显著线性关系（p < 0.001）。对于电子密度P-e/P-e、P-w，每种参考材料的PE在-2.0至1.2%（平均值，< 0.1%）之间变化，对于原子序数Ze（ff），PE在-6.4至8.0%（平均值，-2.0%）之间变化，并且对于阻止功率比SPRw，PE在-2.0至1.9%（平均值，0.3%）之间变化。结论：DLCT测量P-e/P-e、P-w、Z（e）（ff）和SPRw具有较高的准确性，可提高放射治疗计划的制定和疗效。
Purpose: Assess the accuracy for quantitative measurements of electron density relative to water (P-e/P-e,P-w), effective atomic number (Z(eff)) and stopping power ratio relative to water (SPBw) using a dual-layer computed tomography (DLCT) system.Methods and Materials: A tissue characterization phantom was scanned using DLCT with varying scanning parameters (i.e., tube voltage, rotation time, CTDIvol, and scanning mode) and different reference materials. Then, electron density P-e/p(e,w) and atomic number Z(e)(ff) images were reconstructed, and their values were determined for each reference materials. Based on these two values, SPA(w) was calculated. Finally, the percent error (PE) against the theoretical values was calculated for reference materials.Results: Significant linear relationships (p < 0.001) were observed between the measured and theoretical p(e)/ p(e,w) (r = 1.000), Z(e)(ff) (r = 0.989) and SPA(w) (r = 1.000) values. The PE for each reference material varied from -2.0 to 1.2% (mean, < 0.1%) for electron density P-e/P-e,P-w, from -6.4 to 8.0% (mean, -2.0%) for atomic number Ze(ff), and from -2.0 to 1.9% (mean, 0.3%) for stopping power ratio SPRw. The mean PE of P-e/P-e,w ( < 0.1%), Z(e)(ff) ( < -2.5%) and SPA(w) ( < 0.4%) was verified across the variation of scanning parameters (p > 0.85).Conclusions: DLCT provides a reasonable accuracy in the measurements of P-e/P-e,P-w, Z(e)(ff) and SPRw, and could enhance radiotherapy treatment planning and the subsequent outcomes.